Preliminary Analysis of a Mandrel for 105mm Gun Tube Forgings
Abstract
A simplified stress analysis of a mandrel used in rotary forging of 105-mm M68 gun tube forgings is presented. High tensile stress occurs at the inner bore during a fraction of a forging cycle when two hammers are engaged with the billet. The combination of the tensile stresses due to mechanical and thermal loading is responsible for the fracture of the mandrel. Assuming a semi- circular crack initiated at the inner bore of the mandrel and propagated in the radial direction, the stress intensity factors are computed based on the penny shaped crack under arbitrary loading. The remaining life of a mandrel having a semi-circular crack of 0.003 inch is predicted based on the most severe loading conditions and using the propagation equation for gun steel. The effect of the reduction of the inner diameter of the mandrel on the mandrel life is studied. A four-fold life increase is predicted if the bore diameter is reduced from 1.969 to 1.4 inches. The effect of autofrettage is also studied. The mandrel life can be increased as much as 48 times if the mandrel is overstrained 50 percent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1979
- Accession Number
- ADA072814
Entities
People
- J. D. Vasilakis
- L. S. Pu
- M. A. Hussain
Organizations
- United States Army Armament Research, Development and Engineering Center